Canon in D
by xxLittle Black Dressxx
Summary: When Derek goes to L.A. for Amelia's wedding, he and his sisters find themselves reminiscing about their own weddings, causing old memories and unexpected feelings to resurface. Addison/Derek; Addison/Jake.


A/N: I've been having a little trouble feeling motivated to write since finishing my last story, The Shepherds. So I decided to try to break my writing rut by writing a story that combined a bunch of my favorite things (Addison, Derek, Jake, the Shepherd sisters, and flashbacks). It ended up being a lot longer than I had anticipated – mostly because I kept going back and adding flashbacks – but it didn't feel right breaking this story up into chapters. I hope you like it. And, as always, thanks so much for reading!

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**Canon in D**

"Derek, I'm so glad you made it," Carolyn smiled, as Derek sat down in between her and Nancy.

"Of course I made it," Derek insisted. "Amelia's getting married today. I wouldn't miss that."

"Hmm, I'm not so sure about that," Nancy muttered under her breath; and Derek rolled his eyes at his sister's implicit accusation.

But as much as he hated to admit it, Nancy's quip wasn't entirely unjustified. Over the past several years, Derek hadn't exactly made his sisters a priority. He hadn't been home since his divorce. And he was never the one to initiate visits or calls with his sisters. Truth be told, he couldn't remember the last time he'd talked to Nancy or Kathleen; and the only reason he'd seen Lizzie and Amelia relatively recently was because they'd come to him.

"So, you're flying solo today?" Lizzie asked from her seat next to Nancy, pointing out the obvious fact that Derek was Meredith-less and childless. "I was hoping to meet your kids."

"And I've never met your wife," Kathleen, who was sitting next to Lizzie, added.

Derek ran a hand through his hair. As the only brother among four sisters, he was used to being ganged up on; but he'd forgotten just how overwhelming his sisters could be sometimes.

"Meredith's best friend, Cristina, is moving across the country next week," Derek explained. "So, she and the kids are back in Seattle spending time with Cristina before she leaves."

"Oh," Nancy said smugly, shooting Derek a pointed, disapproving look; and Derek couldn't help but notice the almost identical looks on Lizzie and Kathleen's faces.

"Hey, maybe we'll see them next time," Kathleen chimed in with feigned cheerfulness.

"Yeah, maybe," Lizzie echoed doubtfully.

Derek sighed in frustration. His sisters didn't get it. They didn't know Meredith (admittedly, through no fault of their own). But, still, they didn't get her. They didn't get that Cristina was her family in a way that Amelia, or anyone else, never would be. And in all honesty, the whole situation probably would have been fine, except for Addison – the constant thorn in his side. Because, of course, Addison and Amelia had a wonderful relationship. Addison had always had a wonderful relationship with all of his sisters. And this made the essentially non-existent relationship that he and Meredith had with his sisters seem even more inexcusable.

"So, how are the kids?" Carolyn asked Derek, doing her best to change the topic and save her son from the condescension and scrutiny that his sisters were currently putting him through.

"They're good," Derek smiled. "Zola started pre-school, and Bailey's starting to walk and talk." He turned his attention to his sisters. "Are your kids here?" He knew it was wrong of him, but he secretly hoped that they'd say 'no,' so he wouldn't look as bad for not showing up with his wife and children.

"They're over there," Nancy said, gesturing across the aisle, and Derek followed her gaze to see his nieces and nephews and his brother-in-laws.

"They became friends with Angela, last night, at the rehearsal dinner," Lizzie explained. "And they wanted to sit near her today. And we figured it was a pretty harmless request."

"Angela?" Derek asked in confusion.

"Jake's daughter," Nancy explained. She gave her brother a smug smirk. "Don't tell me you don't know who Jake is."

Derek did his best not to roll his eyes at that. He knew who Jake was. The guy who had replaced him in more ways than one. For starters, he was Addison's husband. But he was also the man who would be giving Amelia away. It didn't matter to Amelia that Derek had given all of his other sisters away on their wedding days; she wanted Jake to give her away. Because Jake was the only one that she had let help her when she was pregnant with her brainless baby. Because her coffee dates with Jake had been one of the only things that had kept her from using again when her life had become a circus and was spiraling out of control. Because Jake was the one who had first convinced her to give James a chance. And because, over the years, Jake had become her family. Derek knew that Amelia loved him and that he'd always be her brother – she'd told him as much on the phone when she called to tell him that she'd asked Jake to give her away, and that she hoped he'd understand – but it still kind of hurt.

"Jake's daughter has a kid?" Derek asked, squinting, trying to get a better look at the baby nestled contently in Angela's arms.

Nancy shook her head. "No. She's holding Addison and Jake's daughter, since Addison, Jake, and Henry are all in Amelia's wedding."

"Oh," Derek muttered flatly. He'd heard about Henry. Addison had mentioned him during one of their phone calls, when they were grieving Mark's death together. And, now that he thought about it, he kind of remembered overhearing talk about Addison's daughter as well – bits and pieces of a conversation between Callie and Bailey; and Richard saying something to Alex Karev (of all people) about Addison and the most beautiful baby he'd ever seen. At the time, Derek hadn't put two and two together; but now it all made sense.

"Her daughter's nothing special," Carolyn sniffed.

"Are you kidding me?" Lizzie disagreed. "Her baby's gorgeous."

"She is," Nancy agreed. "She looks exactly the way I always imagined Addison's daughter would look."

Derek shot Nancy a confused look. "Why were you imaging what Addison's daughter would look like?"

"Derek, you were married to Addison for eleven years," Nancy pointed out. "And the two of you are genetic goldmines. It's only natural that people thought about what your kids were going to look like."

"I know I did," Kathleen piped up.

"I didn't," Carolyn shrugged.

"Well, you're alone there, Mom," Lizzie insisted. "Because the three of us and Amelia definitely did."

Derek hated to admit it, but Lizzie was right – his mother really was alone in not thinking about what his and Addison's kids might look like. Because he too had spent a considerable amount of time thinking about it, once upon a time.

The sound of soft music playing ripped Derek from his thoughts; the wedding was beginning. He watched a man, who he could only assume was James, walk down the aisle first.

"Is that Charlotte King?" Derek whispered to Nancy, discretely gesturing towards the petite, blonde woman who was making her way down the aisle.

"It is," Nancy confirmed. "You know her?"

"She and her husband came to Seattle with Amelia a couple of years ago," Derek explained. "I didn't realize that she and Amelia were close friends."

"Charlotte's one of Amelia's best friends," Nancy whispered. She turned to Derek, a smug smile on her face. "Hey, do you remember my wedding?" she asked. "And how you and Addison had only recently started dating, but you two pretended to just be friends so that she wouldn't have to deal with the entire family fussing over her."

Derek couldn't help smiling at the memory. "Yeah," he chuckled. "That day is kind of hard to forget."

"_So, your family doesn't know we're dating?" Addison asked Derek in confusion, as they walked together, hand in hand, towards the church where Nancy would soon be getting married._

_Derek shook his head. "They don't," he admitted, squeezing his girlfriend's hand reassuringly. "And it's not that I don't want them to know," he added quickly. "Because I do. It's just…my sisters are ridiculously nosey, and they always make a big fuss whenever I introduce them to a new girlfriend. And things with us are going really well, and I guess I didn't want you to get scared away."_

"_Derek," Addison laughed, meeting her boyfriend's eyes. "I'm not going to get scared away. Besides, I'm sure your sisters aren't any worse than Archer."_

"_I guess you're right," Derek conceded. "But Archer's only one person. I have four sisters. Four incredibly judgey and prying sisters, who will overwhelm you with never-ending questions and stories and-" _

"_And they sound great," Addison finished with a smile. "But you know, it could be fun to pretend we're not dating…to keep things a secret just a little longer."_

"_I like that idea," Derek approved. "And then we'll be able to actually enjoy Nancy's wedding, instead of being hassled to death about how long we've been dating, and where you're from, and what type of doctor you want to be, and whether or not you want kids one day."_

"_Your sisters wouldn't ask me if I want kids," Addison insisted. "At least, I'm assuming they'd hold off on asking a question that personal until they get to know me better."_

_Derek shook his head. "No," he chuckled. "They've asked previous girlfriends of mine that question very early on…too early on."_

"_Previous girlfriends?" Addison asked, raising an eyebrow. "So you introduce a lot of girlfriends to your sisters?"_

"_Not a lot of girlfriends," Derek backpedaled. "And I don't know…" he trailed off, meeting Addison's eyes, "I have a feeling that you're going to be the last girlfriend I ever introduce them to."_

_xxxxx_

"_Is there a reason that your sisters are staring at us?" Addison asked Derek, as they swayed to the music together at Nancy's reception._

_Derek discretely maneuvered himself and Addison so that he could get a better glimpse of his sisters, who sure enough, were staring at him and Addison, and making their way towards them._

"_You two definitely aren't just friends," Nancy accused, once she was in earshot of Derek and Addison._

"_Shouldn't you be enjoying your wedding?" Derek quipped evasively._

"_I am enjoying my wedding," Nancy shot back. "But I also know that you two are more than friends."_

"_She's right," Lizzie agreed. "You two are dancing way to close to just be friends."_

"_And Derek's dancing," Kathleen pointed out. "Derek hates dancing in public." She turned to her brother. "You've pretty much been on the dance floor all night."_

"_That's true," Amelia agreed. She turned to Addison and smiled. "Derek must really like you."_

"_So…" Lizzie prodded, looking from Derek to Addison._

"_Okay, we're dating," Derek confessed, unable to keep the smile off his face. "We've been dating for a couple of months."_

"_And you didn't tell us?" Lizzie asked in surprise._

_Derek shrugged helplessly._

"_Derek, you should have told us," Nancy rebuked. "I mean, you're clearly happy. You're dance-in-public happy." She turned to Addison. "Has he sung for you yet?"_

"_What?" Addison asked in confusion._

"_Derek doesn't dance in public, and he doesn't sing," Nancy explained. "But, with you, apparently, he dances in public. So, I was just wondering if he sings for you too."_

_Addison shook her head. "He hasn't."_

"_Can we please go back to enjoying your wedding, Nancy?" Derek cut in, desperate to make the conversation less awkward for himself and Addison._

_Nancy sighed. "I really should get back to my husband and our guests," she admitted. She turned to Derek and Addison and smiled. "But don't worry; there'll be plenty of time for me to ask you more questions later."_

"It was so obvious that you and Addison were something serious," Nancy whispered to Derek. "Nobody was fooled by your whole 'we're just friends' act."

"Well, you can't blame me for trying," Derek defended. "I was trying to spare Addison from your prodding and questions and judging. Not that it worked," he muttered dryly.

"Derek, we're your sisters," Lizzie grinned. "Prying and judging and prodding…it's what we do. And we liked Addison right off the bat, so we really weren't that bad."

"We really did like Addison," Kathleen agreed. "I mean, Lizzie and I both asked her to be a bridesmaid in our weddings."

"You did a lot more than that, Kath," Derek said quietly, meeting Kathleen's questioning gaze. "The bouquet," he went on vaguely.

Kathleen's eyes widened in surprise. "You saw that?"

Derek was about to respond, but Lizzie was quicker. "Wait, I don't think I've heard that story," she cut in.

"It was nothing," Kathleen said dismissively.

Derek was prepared for Lizzie to press the issue further. And ordinarily she would. But she was distracted by Henry and Mason, Amelia's ring bearers, who were making their way down the aisle.

"The smaller one is Addison's son, Henry," Lizzie whispered to Derek. And Derek had to admit Henry was undeniably adorable.

He watched Henry for a moment, when Kathleen cut into his thoughts. "So, you really saw that whole thing with the bouquet?" she whispered discretely.

Derek swallowed hard before meeting his sister's eyes. "Yeah," he whispered back. "I did."

"_Hey, Addie," Kathleen said, beckoning Addison over to her. And Derek watched as his girlfriend walked across the dance floor, over to where his sister was standing._

"_So, here's the thing," Kathleen began, as she smoothed down her wedding gown. "I hate bouquet tosses. I think they're tacky and demeaning. And I'd rather not watch all my single friends fight over who's going to be the next to get married."_

_Addison chuckled at Kathleen's logic. "Hey, it's your wedding," she reasoned. "If you don't like the bouquet toss, it's your right not to do it."_

"_The thing is," Kathleen continued, "I like the significance behind the bouquet toss. So…here," she said, handing Addison her wedding bouquet. "Don't tell Lizzie. But I'm giving you my bouquet because you and my brother are great together, and I hope you're the next one to get married."_

"_Kathleen," Addison choked out, truly touched by Kathleen's gesture. She pulled Kathleen into a tight hug. "Kath, thank you so much."_

_And Derek couldn't help smiling s he watched his girlfriend and sister together. But even more so, he couldn't help smiling because of how in sync Kathleen's feelings about Addison were with his own feelings about Addison. Unbeknownst to anyone but Mark, Derek had recently gone ring shopping, and had picked out the perfect ring. So, unless any of his sisters had a shotgun wedding (he could care less about Kathleen's friends), Kathleen would get her wish – he and Addison would be the next ones to get married. _

"So, wait, what was that story with the bouquet?" Lizzie asked, ripping Derek from his thoughts.

"It's nothing," Kathleen insisted once again. But as Derek met his sister's eyes, they shared a look of understanding…a look that silently communicated that it wasn't nothing. That it was very much something.

But Derek knew that he couldn't think like that. So, he redirected his attention towards the aisle, reminding himself that nothing good could possibly come from thinking about the past; that the present was very good, and he should focus on that. Unfortunately, that wasn't exactly going to be an option for him because walking down the aisle was one of his biggest connections to the past – Addison.

To say she didn't look beautiful would be a blatant lie. To say that watching her didn't stir up a flurry of pleasant memories wouldn't exactly be truthful either. And as he watched his ex-wife, he couldn't help thinking about the time that Addison had walked down the aisle as a bridesmaid in Lizzie's wedding. But as his eyes traveled down to the large, emerald-cut diamond on Addison's ring finger, he knew that this was nothing like Lizzie's wedding. Because at Lizzie's wedding, he and Addison were married, and she was wearing his wedding and engagement rings. This time, they were both married – just to other people.

"She's such a bitch," Lizzie muttered, cutting into Derek's thoughts.

"What?" Derek asked in surprise. With the exception of her culinary skills at the Hotdog Thanksgiving, he couldn't remember ever hearing his sisters criticize Addison. Even when she'd slept with Mark, they hadn't judged her too harshly.

"You're ex-wife's a bitch," Lizzie repeated. "I mean, I love her to death; but she gave birth like, what, five months ago, and she already has her figure back. It took me almost a year to lose all the baby weight after I had Jessica."

"Hey, the way I see it, you were just lucky you fit into your wedding dress," Derek quipped.

"Shhh," Lizzie warned, bringing her index finger to her lip. "Mom doesn't know about that. And I'd rather her not find out today…or ever." She shook her head in amusement as she met her brother's eyes. "I can't believe you remembered that."

"Lizzie," Derek chided. "How could I not remember that?"

"_I think I'm gonna be sick," Lizzie groaned, as she rushed towards the bathroom, getting there just in time to vomit violently into the toilet._

"_Hey, it's okay. You're okay," Addison reassured, rubbing soothing circles on her sister-in-law's back. "It's perfectly normal to be nervous on your wedding day." She looked up at Derek, who was lingering outside the bathroom doorway, a concerned look on his face. "Hey, Honey, would you mind getting us a bottle of water?"_

_Derek nodded, and quickly returned with a bottle of water to find Lizzie hunched over the toilet expelling the contents of her stomach. He met Addison's eyes, and the two of them exchanged a worried glance. "Here," he said, handing his wife the water, so that she could give it to Lizzie._

"_Thanks," Addison nodded. She turned her attention to her sister-in-law. "Lizzie, how long have you been feeling like this?" she asked gently._

_Lizzie sighed before meeting her brother and sister-in-law's eyes. "About a month," she muttered dryly. "Pretty much all morning, every morning, for the past month, like clockwork."_

"_So, wait," Addison began cautiously, looking from Derek to Lizzie. "Are you saying that you're…?"_

"_Pregnant." Lizzie filled in. "Yes. But nobody knows. And I'd prefer to keep it that way."_

"_We won't say anything," Addison promised. She squeezed her sister-in-law's arm warmly. "Congratulations," she smiled, meeting Lizzie's eyes. "I'm really happy for you…and Tom. Tom knows, right?"_

_Lizzie chuckled. "Of course Tom knows. I just…no one else can know. They'd judge me."_

"_Nobody would judge you," Derek insisted. "Our family's not like that. Now if you were part of the Montgomery family…" he trailed off, meeting Addison's eyes; and the two exchanged an amused look, knowing that something like this would absolutely never fly with Addison's ridiculously image-conscious family._

"_I don't care," Lizzie insisted. "You wouldn't get it, Derek; you're the favorite. You can do no wrong. The rest of us…we're held to different standards. So, nobody's finding out, okay?"_

"_Okay," Derek agreed quickly._

"_Thank you," Lizzie sighed. She was about to say more when Kathleen and Nancy joined them in the bathroom._

"_Lizzie," Nancy began, "the make-up artist is here to do your make-up."_

"_And your hairdresser is outside waiting too," Kathleen added. "So, you really should…did someone just vomit in here?" she asked cutting herself off._

"_I, uh," Lizzie stammered, as she looked from Nancy to Kathleen, who were both eyeing her suspiciously. "Um, I…"_

"_I did," Addison cut in._

_Lizzie breathed a sigh of relief, and Nancy and Kathleen immediately turned their questioning gaze to Addison. "Are you okay?" Nancy asked her sister-in-law in concern._

"_I'm fine," Addison assured her. "I just…Derek and I were in a rush this morning, so we stopped at McDonalds for breakfast. And I don't normally eat fast food, so…"_

"_Derek ate McDonalds?" Nancy asked in surprise. "He always eats healthy."_

"_Oh, no, Derek didn't get anything," Addison said quickly. "And I probably shouldn't have either. But I'm fine now," she reassured her sister-in-laws, hoping that she was being convincing. _

"_You really do look better," Lizzie agreed, shooting Addison an appreciative look. And Derek had to bite his lip to keep himself from laughing at the ridiculousness of the whole situation._

"_I feel better," Addison nodded. "So," she began, giving Lizzie a genuine smile, "let's get you ready to get married."_

"_Okay," Lizzie agreed. "Hey, Nancy, Kathleen…can you tell the hair and make-up people that I'll be right out?"_

"_Sure," Nancy agreed, as she and Kathleen turned to leave._

_Once they were out of earshot, Addison turned to Lizzie. "Still feeling sick?" she asked sympathetically._

_Lizzie shook her head. "No. I just…" she trailed off, meeting Addison's eyes. "Thank you."_

_Addison smiled at her sister-in-law warmly. "Anytime."_

"Addison really was awesome at my wedding," Lizzie grinned. "And she was so convincing."

"A little too convincing," Derek muttered. "After your wedding, Addison and I spent weeks convincing the family that _she_ wasn't pregnant, thanks to a rumor that Kathleen started."

"Can you really blame me?" Kathleen shrugged innocently. "At the wedding, I saw her order a champagne flute filled with ginger-ale. And I knew that she'd been sick earlier that morning. And I'm sorry, Derek, but that whole McDonalds story that she told didn't seem believable. So I jumped to the only logical conclusion. I had no idea that she was covering for Lizzie."

"You're supposed to be a shrink, Kath," Derek teased. "You're supposed to be observant."

"Hey, I was observant," Kathleen defended. "I just didn't connect my observations correctly."

Derek chuckled. He was about to say more, but everyone's attention turned towards the back of the room. Amelia was walking down the aisle.

Amelia looked beautiful. Derek knew she would. But what he was more interested in (perhaps, pettily so) was Jake.

"He's hot," Lizzie murmured appreciatively.

"You're married," Derek whispered, not taking his eyes off Amelia and Jake.

"I know," Lizzie said innocently. "I was just saying."

Derek hated to admit it, but Lizzie was right; Jake Reilly was attractive. But what's more, he was supposedly a really good guy. He had helped Amelia get through what he could only imagine had to have been hell on earth. So, even though he wanted to hate Jake Reilly, he knew he couldn't.

But what he could – and did – hate was that he was not the one who was walking Amelia down the aisle and giving her away. Derek knew that if he had tried harder, and made Amelia a priority, things would be very different, and he would be the one giving her away. Just like he gave all of his other sisters away. Because the past few minutes had made him realize how easy it was for him and his sisters to fall back into their old relationship – the relationship they'd had before Seattle, before the cheating, before the divorce. Of course, all of the memories that he and his sisters had bonded over revolved around Addison – but he tried not to think about that too much.

Against his better judgment, Derek looked over at Addison, who was standing at the altar, a loving smile on her face, as she watched her husband and the woman, who over the years, had become her sister walk down the aisle together. And for the first time, Derek truly understood how ignored Addison must have felt back in New York and Seattle. Because if she noticed him, she wasn't letting on; her attention was too wrapped up in Jake and Amelia, and her new life. It's not that Derek was expecting Addison to fuss over him, but some form of acknowledgment would have been nice. After all, he'd spent the better part of Amelia's wedding thinking about her.

"You know," Nancy whispered to Derek, "not that it's a contest or anything, but your wedding was, hands down, the most beautiful wedding I've ever been to."

And even though he knew he shouldn't, Derek couldn't help smiling at his sister's compliment. "You and me both," he said quietly. He didn't feel bad about saying it either; because even though his and Addison's marriage had ended, their wedding was – and would always be – undeniably beautiful. But the funny thing was that as beautiful as their wedding was, the thing that he remembered most vividly about his and Addison's wedding was the night before.

"_Derek, are you awake?" Addison whispered._

_Derek rolled over in bed to face Addison. "Yeah," he whispered back. "You okay?"_

"_Yeah," Addison nodded. "It's just…it's midnight. We're getting married today. Happy Wedding Day, Honey."_

_Derek smiled before leaning in and kissing Addison deeply. "Happy Wedding Day," he breathed when they broke apart. "So…" he grinned, sitting up in bed, suddenly feeling wide-awake, "are you nervous?"_

"_About getting married?" Addison asked._

"_Yeah."_

_Addison shook her head. "No. Because it's you and me. And we've been through a lot together. Med. School, our internship year, the medical boards. And we've still got a lot to come…finishing residency, fellowships, becoming attendings, and hopefully kids someday."_

"_Definitely kids someday," Derek smiled, kissing Addison softly._

"_Yeah," Addison agreed with a smile. "So, what about you? Are you nervous?"_

"_I'm not nervous about marrying you," Derek grinned. "I've never been more certain of anything in my life."_

"_But you're nervous about something," Addison assessed knowingly. _

"_I am nervous about something," Derek admitted, smiling at just how well Addison knew him. He hesitated for a moment before deciding to confide in Addison. "I wrote you song," he confessed. "And I'm going to sing it at the wedding."_

"_Really?"_

_Derek nodded. "I mean, I'm no John Lennon or anything," he chuckled. "But I wrote a song about you a while back…and, uh, I kind of like it."_

_Addison smiled at her soon-to-be-husband lovingly. "Can I hear it?" she asked hopefully._

"_You don't want to wait until the wedding?"_

_Addison smiled. "All of our family and friends will be at the wedding. So while it'll still be personal, it'll be less personal than if you sang it just for me tonight."_

_Derek nodded, following Addison's line of reasoning. "Okay," he agreed. He smiled at Addison adoringly, knowing that she was the only woman he'd ever do anything like this for, before singing the opening verse of his song._

"_Our eyes met over the cadaver.  
__And I knew I had to have her."_

"Derek," Nancy whispered, nudging her brother. "The wedding's over. Come on, everyone's heading over to the reception now."

"Oh," Derek stammered, standing up and following Nancy down from the rooftop of the hotel, where Amelia's wedding ceremony had been held, to the hotel ballroom, where the reception was being held.

And before Derek knew it, the wedding reception was underway. He sipped at his scotch, picked at his salad, and reluctantly danced with his mother and sisters. But about half way through the wedding, Derek needed some air. Apparently, all of the memories and reminiscing had gotten to him more than he'd anticipated, and he needed a couple of minutes to himself. So, he left the ballroom and wandered into the hotel lobby, and sat down on one of the fancy couches there.

He'd only been sitting there a couple of minutes, when he heard Addison's unmistakable voice.

"Hey, it's okay, Thora," Addison reassured the fussy baby in her arms. "It's okay, Sweetie."

Derek sat there for a moment, just watching Addison soothe her daughter, until Addison finally noticed him sitting there.

"Derek," she smiled. "What are you doing out here?"

Derek gave her a warm smile. "You know how overwhelming my family can be," he chuckled. "I just needed a minute alone."

"Oh, sorry, I didn't realize…" Addison stammered. "I could leave so that you can be alone, or I-"

"Stay," Derek smiled, patting the space next to him on the couch. He smiled at the baby in Addison's arms. "It looks like she could use a little time away from everyone too."

Addison chuckled. "I don't know what I was thinking bringing a five-month-old to a wedding," she admitted as she sat down on the couch next to Derek.

"She was really good during the ceremony," Derek pointed out.

"That's true," Addison agreed.

"What did you say her name was?"

"Thora," Addison smiled. "Thora Vivian."

Derek's eyes softened at the name. "Vivian after-"

"My mentor," Addison filled in. "My late mentor," she added quietly.

"I'm sorry," Derek said gently. He knew how much Vivian had meant to Addison.

"Thanks," Addison nodded as she rubbed Thora's tiny back soothingly.

"She's really beautiful, Addison," Derek said sincerely, unable to tear his eyes away from Addison and Thora. "She looks just like you. Your son's adorable too," he added.

"Thank you," Addison smiled. "Are your kids here?"

Derek shook his head. "No. The kids and Meredith are back in Seattle. Cristina's moving across the country next week, so Meredith wanted to spend time with her before she leaves."

"Oh," Addison said sympathetically. "That can't be easy for her."

Derek smiled at his ex-wife's words, knowing that no matter how many women came and went in and out of his life, Addison would be the only one who understood both his past and his life in Seattle.

"So, it looks like LA's been good for you," Derek assessed, as he continued to take in his ex-wife and her daughter.

"Yeah," Addison smiled. "It's been-"

But she was cut off by the sound of her cell phone vibrating in her purse.

"Just a second," she told Derek apologetically, as she struggled to simultaneously hold her daughter and open her purse.

"Here, let me hold Thora," Derek offered.

Addison looked at her ex-husband questioningly. "Are you sure?"

"Addison, of course I'm sure," Derek insisted, smiling when Addison finally gave in and gently placed her five-month-old in his arms.

"Hey, Thora," he cooed quietly, so as not to distract Addison from her phone call. And Derek had to admit, Thora was even more amazing up close. With Addison's bright red hair and pale, blue-green eyes, and the sweetest little smile, Thora was an undeniably beautiful baby.

"Is everything alright?" Derek asked Addison when he noticed that she was off the phone.

Addison nodded. "Just a resident calling to update me about a patient."

"Oh," Derek said quietly, as he cuddled Thora close.

"Hey, you're really good with her," Addison complimented as she watched her daughter snuggle deeper into Derek's arms. "She really seems to like you."

"Yeah," Derek said softly. "I really like her too."

He met Addison's eyes, but both quickly looked away, knowing that they were both thinking the same thing…that had things gone differently, this easily could have been the two of them and their baby.

Derek swallowed hard, knowing that he and Addison probably shouldn't be thinking that thought. He was married, and so was she; and they both had families. But, then again, he and Addison had spent eleven-plus years together, so maybe that made it okay. And it's not like they hadn't thought about it before.

"_I don't know what's wrong with me," Addison groaned, as she vomited into the toilet for what had felt like the hundredth time that morning._

_Derek nodded mutely, as he sympathetically rubbed his wife's back, as she continued to expel the contents of her stomach into the toilet._

_Addison took a shaky breath, doing her best to regain her composure before leaning against her husband weakly. "I don't know what's going on with me," she admitted. "I must have the flu or something."_

"_Maybe," Derek said coyly._

"_Honey, I'd rather you not take that smug tone with me when I'm sick."_

_Derek chuckled as he brushed a stray piece of hair out of Addison's face. He met her eyes and gave her a soft smile. "Maybe you're not sick."_

"_Derek, were you not just in here with me? I'm definitely sick."_

"_Maybe," Derek shrugged. "Or you could be pregnant."_

_Addison's eyes widened in surprise. "What?" she breathed._

"_I mean, it's a possibility," Derek explained. "You've been vomiting. And we haven't exactly been careful lately." He pressed a kiss to Addison's temple. "It could be pretty great."_

_A small smile spread across Addison's features. "Yeah," she agreed. "A little unexpected…and maybe a few years earlier than we were planning on…but, yeah, it could be pretty great."_

_In the end, it turned out that Addison wasn't pregnant. That it was just the flu – a horrible case of the flu that had Addison bedridden for a week-and-a-half._

"_Derek you probably don't want to come too close," Addison warned, when Derek climbed into bed next to her. "I don't want you to get sick too."_

"_I'm not afraid of getting sick," Derek shrugged, as he moved closer to Addison. "Besides, I got a flu shot, so I should be okay."_

"_It sounds like you're tempting fate to me," Addison chuckled weakly. She met his eyes, and quickly grew serious. "I'm sorry."_

"_For what?" Derek asked in confusion. "For getting sick? Addison, you couldn't control that. I mean, yes, you probably should have gotten a flu shot, but this isn't your fault."_

"_I wasn't talking about that," Addison said quietly. She swallowed hard. "You wanted a baby. I'm sorry."_

"_Addison," Derek chided, wrapping his arms around his wife. "You have nothing to be sorry about. I mean…yes, I would have been thrilled if the pregnancy test had been positive. But it's gonna happen for us. We're going to get our baby. And, hey, now we can even prepare for her a little better."_

"_Her?" Addison asked, a small smile coming to her face._

"_Yeah," Derek nodded. "I think our first child will be a girl. Hopefully with your hair and your eyes."_

_Addison laughed. "You know, I always pictured us having a daughter who had your hair and my eyes."_

"_Well, we'll just have to have two daughters then," Derek grinned. "That way we can have a mini-Addie and a mixture of the two of us. Oh, and we should probably have a son too." _

_Addison laughed at her husband's enthusiasm. "It sounds pretty great," she admitted, as she thought about the life that Derek had envisioned for them._

"_Yeah," Derek agreed. "It sounds pretty perfect."_

"There you are," Nancy's voice rang out, ripping Derek from his thoughts.

"Addison, we've been looking all over for you," Nancy continued. "It's almost time for you to give your maid of honor speech."

"Oh," Addison stammered.

Nancy looked from Addison to Derek, who was still holding Thora. "What's going on here?" she asked smugly.

"Nothing," Derek said quickly. Probably too quickly.

"Okay, right," Nancy smirked, clearly unconvinced. "So, Addison, are you coming?"

"Um, yeah," Addison nodded, getting up off the couch. She hesitantly reached for Thora, as if internally debating whether or not she should bring her five-month-old back into the ballroom.

"I can stay here with her," Derek offered, sensing his ex-wife's reservations.

"Derek, you don't have to do this," Addison insisted.

"I know," Derek nodded. "But I want to. Besides," he added with a smile. "I could use the company."

"Okay," Addison agreed. "Thank you. I'll send someone out here to get her," she promised, as she walked away with Nancy.

Derek watched Addison's retreating form before turning his attention back to Thora. He had expected the five-month-old to cry when her mother left, but she didn't. She seemed perfectly content in his arms.

"So…Thora…" Derek cooed, as he gently stroked Thora's baby-soft cheek with the back of his index finger. "That's a pretty grown up name for a little baby. But I like it," he added quickly. "It fits you."

He sat there for a little while, completely enamored with the baby girl in his arms, when the sound of approaching footsteps brought Derek back to reality; and Derek looked up to see Jake walking towards him.

"Hey," Jake smiled. "Addison told me you were out here with her. And we didn't know how badly you wanted to get back to the reception, so I figured I'd give you that option if you wanted it."

Derek chuckled. "I'm actually kind of enjoying myself out here with her," he admitted. He looked down at Thora and then back at Jake. "She's beautiful."

"Thank you," Jake grinned proudly. "I'm pretty taken with her. And thank you for watching her while Addison gave her maid of honor toast."

"I was happy to do it," Derek insisted. "Like I said, I'm having a good time hanging out with her."

"Well, I appreciate it," Jake said genuinely.

"It's the least I could do," Derek said vulnerably. "I mean, you really stepped up with Amelia. You didn't have to do that. So, if anything, I should be the one thanking you."

"Hey, I was happy to do it," Jake said, echoing Derek's words. "Your sister's an incredible woman. And it's nice to see her living the type of live she deserves." He met Derek's eyes and smiled. "You know, I'm really glad I got to meet you today."

"Why?" Derek asked dryly. "So you could finally meet the guy who was stupid enough to be indifferent towards your wife?"

Jake shook his head. "No. Because you seem like a good guy. And because you'll always be an important person in Addison and Amelia's lives. And they both mean a lot to me. So, I'm glad I got to meet you."

Derek sighed heavily. He hated to admit it, but Jake really was a good guy. Too good, even. "I'm glad I got to meet you too, Jake."

Jake gave Derek a warm smile.

"You know," Derek began, "you don't have to sit out here with me. You should go enjoy the party."

"Are you sure?"

Derek nodded. "Yeah. Go. They're mostly your friends in there anyway. And me…well, I like Thora a lot more than most of the people in there, so I don't mind watching her. So, go. Have fun."

"Thank you," Jake said sincerely. "But if she gets fussy, come get me. Thora's got a pair of lungs on her, and you didn't sign up for that."

"Okay," Derek chuckled.

"Thanks again," Jake smiled. He turned his attention to Thora. "See you soon, Sweetie," he cooed, pressing a kiss to her temple. "Be good for Derek."

Derek watched Jake walk away before turning his attention back to Thora. "You have a good dad," he told the baby in his arms. "Because, in all honesty, I wasn't a great husband to your mom; and lately, I haven't been much of a brother to your Aunt Amelia. And most guys in your dad's position would probably either want to deck me, or not give me the time of day. But your dad's clearly not most men. I mean, most men would have their reservations about letting their wife's ex-husband watch their baby. I guess he and your mom must have a really trusting, grownup relationship." He looked down at Thora, who was gurgling happily in his arms. "And you have no idea what I'm talking about, do you?" Derek cooed with a chuckle, as he cuddled Thora close.

"Hey, Thora," he grinned. "What do you say we check out the party?"

He walked back into the ballroom, cradling Thora, and lingered by the doorway as he took in the wedding reception. Amelia and James were on the dance floor, dancing together. And Addison and Jake were dancing together as well, her head resting against his chest, his arms wrapped around her lovingly.

He saw his sisters huddled together, looks of sheer delight on their faces, as they watched him with Thora. He figured the scene was probably triggering some long-lost fantasy of theirs – involving him, Addison, and an adorable kid (or two or three). Okay, maybe it wasn't just his sisters' long-lost fantasy.

He saw his mother, standing near his sisters, watching him, a look of disapproval clear on her face. But Derek didn't care what his mother thought. He looked down at Thora and smiled. Nancy was right about her – she looked exactly the way he'd imagined Addison's daughter would look. Exactly the way he'd imagined _his and Addison's_ daughter would look.

And then, before he could think about what he was doing, he was clearing his throat, and singing softly to Thora.

"_Addison Montgomery.  
__He met her in the summer. She  
__Was cutting up a very dead body."_

It felt wrong and right all at the same time. Derek never sang. Not to Meredith. Not to his own children. But here he was singing to Thora. And maybe, in a weird way, it made sense, since the last person that Derek had sang to was her mother. Maybe that made singing to Thora okay.

And as he smiled down at Thora, Derek couldn't help thinking about something that Addison had said to him several years ago – about how she had put him in a tiny box. At the time, he had just chuckled at the metaphor; and, sure, he'd found it flattering. But times like these – when the past resurfaced – reminded him of how apt her metaphor was. And how two directional.

But he also knew that he and Addison had both moved on. They had both married other people. They both had families with other people. They were both happy. And that's what made times like these – when Addison didn't quite fit in her tiny, little box – hard.

He looked down at Thora, her pale, blue-green eyes staring up at him intently. So much like Addison. He swallowed the lump that had formed in his throat, and did the only thing he could do – he cleared his throat and continued to sing to her.

"_And in her eyes I saw my life.  
__I knew that she would be my wife.  
__And she would breathe the life back into me.  
__For every day until eternity."_


End file.
